Edit - Ok, I knew it this thing will happen as using p*rn is a stop word for Google adsense so the moment I used it in the thread title, adsense stopped showing. 
Good Job Google Adnsense. Now anyway who sees it please do tell me as I am curious to know and wanted to do some more research on this.
Since Indian law do not support any kind of distribution or display of adult online content, it is fairly obvious people will find ways to do it. There are various sites and forums where such distribution is going on freely and such forums having memberships of 200k+ does tell something(actually it tells lot of things). You can find everything in these forums, from pics of movies to videos to torrents.
Some of the forums which are HUGE in terms of traffic and membership are XBoard and MasalaBoard. Most of these boards calls themselves as Desi Masala board Both Boards has alexa rank less than 1000 and though it is hard to find the number of people visiting these 2 sites daily, both have 2k to 3k members online at any time! XBoard has around 3lakh member though the active members will surely be a lot less, same can be said about MasalaBoard. These forums supports all kind of movies and picture sharing by 3rd party image and video uploading sites to keep everything legal.
The domains are registered and the sites are hosted in Non India countries so the owners can not come under any India Law. There are many such masala forums online but I will not post there links for obvious reasons.
Links you may find interesting -
- List of Free Websites for Online Dating in India
- List of all Indian Matrimonial Websites of India
- Best Restaurants in India
- List of Best Restaurants in India
- Maruti will launch its own Small car “A Star”